Apple iBooks obviously isn't the first app for reading and has mostly the same features you'll find in other e-readers. You can add bookmarks, define individual words, do quick Web lookups, and add notes. You also can underline words, sentences, and paragraphs for later viewing. Search features let you find words, phrases, and even specific characters. Most of the major book publishers stock iBooks' digital shelves (Penguin, HarperCollins, Simon & Schuster, MacMillan, and Hachette), which makes the content stack up against competing apps and electronic bookstores. (Disclosure: Simon & Schuster is owned by CNET's parent company, CBS.)
New iCloud support in iBooks 3 lets you set up collections you can sync with all your devices so you can pick up where you left off. All your bookmarks, notes, and the latest page you read are all available when you move to a different device. You can also view all your purchases from any device right on your bookshelf. These are features many people have been waiting for now that a lot of users have both iPhones and iPads, so I'm happy to see them added.
Some users are complaining that iBooks 3 crashes or no longer starts up on the original iPad. Apple has been known to move on from earlier hardware, so it's definitely something to look out for and might be worth waiting for another incremental update before you download the latest version.
iBooks is the go-to reading app on iOS devices, and Apple has done a good job making the interface intuitive and continually adding useful features. If you haven't yet jumped on the e-reading bandwagon, iBooks is a strong offering and is the best place to start on your iOS device.